Can forest fires happen because there is no rain?
Lack of rain will not cause a wildfire, but it increases that chance that an ignition source will find highly receptive fuels to make a fire and cause a fire to be energetic and grow rapidly. As part of assessing fire danger and potential fire severity, fire fighters calculate the “probability of ignition”. During very hot, dry conditions this can approach 100%, so any spark or extreme heat source is likely to start a fire.
If live trees cannot burn how do we have forest fires?
This questions’ premise is incorrect. Live trees can burn.You see, live trees are more resistant to fire (Generally) due to their water content and wet wood, more so after periods of rains. However, there are three major factors that mean live trees can burn, even though they are wet:The first is that they’re not 100% alive. Some branches exist on the tree which are dead and connected or even disconnected but stuck in the branches. Additionally, most trees’ centre is comprised completely of dead wood, so once the fire gets through the outer trunk the inside of the tree is incredibly flammable.The next is that even though they’re wet, with enough heat and fire nearby (Say, fire started on the forest floor using dropped dead branches and leaves as fuel) the wood will dry out and catch alight just like anything else. Adding to this is the fact that the wood is porous, which means although it can be wetter, it also contains fuel for burning (Oxygen) inside.The final factor is the tree species. Depending on which species of tree it is, it will likely have different resistances to fire depending on its evolution. The bark is a major factor in whether or not a tree will easily catch alight. The Melaleuca quinquenervia is the Australian Paperbark tree. Its bark is a thick, dense paper like bark, which means there is less oxygen within the bark and when it does catch alight it burns a lot quicker (Think wood vs paper). This gives the tree a natural resistance to fires for a short time as after enough heat, everything will set alight.
How does a wildfire stop without human intervention? Why hasn't the earth burned over from a fire that happened thousands of years ago (or has it?)
When the wildfire happens, it is my understanding that it can spread only as far as the flammable material, so it would stop once there's nothing more to burn.If the wildfire is getting close to human dwellings, and that area (that geography) is able to combat it, then it will be stopped, otherwise the wildfire will cause damage.With respect to setting the world on fire (it's Monday, so I can totally relate to this idea), there are natural limitations such as rivers and oceans and other bodies of water, plus there is vegetation which contains too much moisture (and won't burn), in addition to the climates which are too wet for fires to spread.If we hypothetically suggest that there could be a wildfire which can burn non-stop, it has to have an eternal source of fuel: without it, it can't sustain itself.If a wildfire erupts in a forest, it will only last until it has something to fuel its flames, this is why a localized fire can't spread: there won't be anything to be burned.If, however, a fire spreads, it leaves ashes of whatever it had burned behind, and these ashes then serve as a fertilizer, and allow for the nature to renew itself with new vegetation: this vegetation will be filled with moisture, so it won't burn very well, and for it to become dry and wildfire-friendly, it would have to grow and then dry out.The fire then needs to return to that spot in order to continue on burning - and this is unlikely to happen since wildfires do not travel in cycles, and a new wildfire is a new wildfire.
Arn't forest fires sometimes a good thing?
You are right on. Forest fires can ARE a good thing. Before humans came to North America much of the continent burned naturally every three years from lightening strikes. The animals, plants, and ecosystem evolved in the presence of forest fires. That is why some plants can not reproduce without a fire opening up their cones and releasing their seeds. Giant Sequoyah trees are an example of this, their cones are called serotenous and they only open after a fire goes over them and opens them up. Wildlife have evolved to survive forest fires. I am a wildlife biologist and part of my job is actually doing prescribed burns to help certain species of birds, mammals, reptiles, and amphibians have the type of habitat they need to survive and reproduce. I can tell you that I have seen many rabbits hunker down during a fire against a downed log and hop away unscathed. Larger mammals run away from the fires. They survive because they have been in forest fires for longer than humans have been in North America. Because humans decided that forest fires were bad people started repressing them and putting them out. This has led to many many years of fuel building up in forest. When a fire is started in places that haven't burned for 20,30, or 40 years the fire has a LOT to burn and can become devasting. So bottom line is - Forest fires can and are good to wildlife and plants. In fact, they help many many species of wildlife and plants.
How hot can a forest fire get?
Take a look at this paper from the Australian CSIRO. They are our government scientists and pretty much lead the world in bushfire ( wildfire) research.Gases from a fire can reach up to 1600 degrees Celsius ( nearly 3000 F), with flames between 600 C at the tips to 1100 C at the base. ( 1100 F - 2000 F)https://blogs.csiro.au/ecos/bush...
Which change will most likely have the greatest effect on environment?
C You seriously has to ask this
What happens if there is no rain?
Things get dry. In the short term, plants that have short root systems will dry up and may go dormant or even die, depending on their drought tolerance. Some plants will have deeper roots that can reach down into shallow ground water reserves. In the long term, those ground water reserves will not be replenished if the rains do not fall and will start to recede. The deep ground water often comes from rains that fell in highlands centuries and millennia ago and slowly moved through the ground to us. So if the rains never come for that time length even these will eventually dry up. All plants will die, except the few we might be able to irrigate using expensive desalinated water. Hopefully some long-term thinking will have allowed us to put off short term profit and spend the money to create those desalination facilities. Otherwise, if the short-term profit motive wins, we all die. Even then, we may not be able to replace the oxygen we consume because it’s the green plants that produce the oxygen for us.